Melamine Sponge Research Articles

One-Pot Preparation of Conducting Melamine/Polypyrrole/Magnetite Ferrosponge

Polypyrrole was deposited in situ on the macroporous open-cell melamine sponge by the oxidation of pyrrole with iron(III) chloride. The oxidant was used in excess, and the reaction mixture after th...

Maximized pseudo-graphitic content in self-supported hollow interconnected carbon foam boosting ultrastable Na-ion storage

Hard carbons are the most promising commercialized anodes for sodium-ion batteries (SIBs). However, it is still a great challenge to design highly stable hard carbon anodes coupled with a large reversible capacity. Herein, a self-supported hollow interconnected carbon foam (HICF) is developed by one-step pyrolysis of a commercial and low-cost melamine sponge. The integration of interconnected network and hollow feature can not only provide strong mechanical stability and additional inner space to effectively accommodate the structural deformation from Na+ insertion/extraction, but also enable fast electron and Na-ion transport to achieve a large reversible capacity. As a result, HICF delivers a large reversible capacity of 306 mAh g−1 at 100 mA g−1 and an ultralong cycle life with 86.4% capacity retention over 1000 cycles at 1000 mA g−1. The superior Na-storage performance is also contributed by the maximized content (63.24%) of pseudo-graphitic phase in HICF realized by tuning pyrolysis time, as the pseudo-graphitic phase could store more sodium ions and maintain more stable microstructure owing to its appropriate d-spacing than highly disordered phase. Furthermore, kinetic analysis based on cyclic voltammetry (CV) and galvanostatic intermittent titration technique (GITT) verifies the adsorption–intercalation mechanism. This work provides a low-cost and high-performance anode candidate for the future practical applications of SIBs.

Reduced Graphene Oxide Aerogel inside Melamine Sponge as an Electrocatalyst for the Oxygen Reduction Reaction

A graphene oxide aerogel (GOA) was formed inside a melamine sponge (MS) framework. After reduction with hydrazine at 60 °C, the electrical conductive nitrogen-enriched rGOA-MS composite material with a specific density of 20.1 mg/cm3 was used to fabricate an electrode, which proved to be a promising electrocatalyst for the oxygen reduction reaction. The rGOA-MS composite material was characterized by elemental analysis, scanning electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. It was found that nitrogen in the material is presented by different types with the maximum concentration of pyrrole-like nitrogen. By using Raman scattering it was established that the rGOA component of the material is graphene-like carbon with an average size of the sp2-domains of 5.7 nm. This explains a quite high conductivity of the composite obtained.

Vortex-assisted solid-phase extraction based on metal-organic framework/chitosan-functionalized hydrophilic sponge column for determination of triazine herbicides in environmental water by liquid chromatography-tandem mass spectrometry

In the presented work, MIL-101(Cr) and chitosan were directly embedded on the skeleton of melamine sponge material using a simple and environmentally friendly method. Chitosan acts not only as an adhesive during the preparation of functionalized sponges, but also as an adsorption adjuvant in herbicide detection. Unlike other polymers, chitosan has excellent hydrophilicity and contains numerous adsorption sites; thus, it enables the sponge material to be used for determination of contaminants in an aqueous phase. Scanning electron microscopic (SEM) analysis showed that the coating material was uniformly distributed on the skeleton of melamine sponge. The prepared material was used as a sorbent in a vortex-assisted solid-phase extraction and combined with high performance liquid phase tandem mass spectrometry for the extraction and trace determination of six triazines in water samples (Atraton, Desmetryn, Prometon, Ametryn, Prometryn and Dimethametryn). Several parameters that affect the extraction efficiencies were investigated. Under the optimal conditions (MIL-101(Cr) loading, 150 mg; sample pH, 7; salt concentration, 0%; adsorption time, 3 min; desorption solvent, 1.5 mL acetonitrile; desorption time, 4 min), the proposed method was successfully used in the determination of trace triazines in five real water samples (drinking water, tap water, lake waters and river water), satisfactory recoveries were obtained in the range of 78.9%–118.6%. The limits of detection of the proposed method in detecting triazine herbicides in spiked water samples ranged from 0.014 to 0.045 ng mL−1.

Superhydrophobic conjugated microporous polymer-coated sponges: Synthesis and application for highly efficient oil/water separation and the recovery of palladium ions

Superhydrophobic conjugated microporous polymer-coated sponges (CMP@sponges) have been synthesized by the in-situ Sonogashira polymerization of monomers with multiple carboxyl or hydroxy functional groups in the presence of melamine sponges in a one-pot synthesis. The water contact angles of CMP@sponges are 150.38 and 153.92°, respectively. Unsupported CMP nanowires with diameters of 50–150 nm are synthesized successfully. CMP@sponges show excellent separation efficiency not only for oil/water mixtures including low-density oils that float and high-density oils that sink (such as gasoline, diesel and common organic solvents) but also for emulsified oils, which are much more difficult to separate with high efficiency (up to 99.81% for a toluene-water emulsion). The absorption capacities of CMP@sponges for oils are exceptionally high (55–122 and 38–94 g/g) and stable after 10 cycles. Judging from the excellent performance of CMP@sponges on oil/water separation, an ultrafast oil-removal setup has been designed that can be used to continuously collect floating oil at high speed and with a high separation efficiency (up to 10.2–16.3 mL/s). In addition, the recovery of palladium ions (Pd(II)) from organic palladium waste solutions by using CMP@sponges has been achieved, and 297 mg/g Pd(II) ions can be adsorbed. This is the first example of a CMP@sponges setup, which can continuously recover oils from oil/water mixtures with high efficiency and can also be used for recovering Pd(II) from organic solvents. The novel CMP@sponges show great application prospects for treatingoil spills and heavy metal pollution.

Characterization and application of superhydrophobic and superoleophilic OTS-LDH/melamine sponge

The n-octadecyltrichlorosilane (OTS) had been coated onto the layered double hydroxides (LDH), and the resultant composite of OTS-LDH was further loaded on the surface of melamine sponge by a soaking method to obtain the OTS-LDH/melamine sponge for efficient oil adsorption in this work. The surface chemical compositions of the OTS-LDH/sponge and its precursors were characterized by EDS, XPS, and FTIR. The results from EDS, XPS, and FTIR showed that the OTS had been successfully coated on LDH. The surface morphologies from SEM for the melamine sponge before and after modification illuminated that the surface skeleton of the OTS-LDH/sponge took a rough micro-nanostructure, and the surface had been loaded with the low surface energy material of OTS, which made the OTS-LDH/sponge display the superhydrophobic properties. The experiments of oil–water separation proved that the OTS-LDH/sponge took an excellent oil–water efficiency, and the modified sponge still took the better oil–water separation performance with an oil adsorption capacity of 13.7–21.1 times of the mass of the pristine sponge even after undergoing repeated extrusion for 60 times during the repeated cycle test.

Partially carbonised melamine sponge coated with metal–organic framework-derived CuCo2O4/C composite as a flexible anode for lithium-ion batteries

The poor conductivity of melamine sponges limits their applications as flexible electrode substrates for lithium-ion batteries (LIBs). Coating metals on the surface of the electrode increases its weight, which, in turn, lowers the capacity. Furthermore, complete carbonisation at high temperatures causes a loss of flexibility. Herein, we report the design and synthesis of a novel flexible anode for LIBs with a metal–organic framework (MOF)-derived CuCo2O4/C composite coated on the surface of a partially carbonised melamine sponge (PCMS). The PCMS gives good flexibility to the electrode and is compatible with growth of a MOF-derived CuCo2O4/C composite on its surface. As a carbon-based composite with good conductivity, the continuous MOF-derived CuCo2O4/C composite coating on the surface of the PCMS considerably improved its conductivity. As a flexible anode for LIBs, the composite with the MOF-derived CuCo2O4/C on the surface of the PCMS had capacities of 521 mAh g−1 and 348 mAh g−1 at current densities of 100 mA g−1 and 2000 mA g−1, respectively. Here, the MOF-derived CuCo2O4/C composite contributed a high capacity of 1002 mAh g−1.

Extraction of Parabens by Melamine Sponge with Determination by High-Performance Liquid Chromatography

Extraction of Parabens by Melamine Sponge with Determination by High-Performance Liquid Chromatography

A facile and efficient universal strategy of superhydrophobic materials based on plant polyphenols as multifunctional platforms

A facile and convenient strategy of superhydrophobic materials has been developed via a step-by-step procedure of dipping in easily available (3-aminopropyl) triethoxysilane (APTES), polyethyleneimine (PEI), larch tannin (LT), FeCl3 and 1-dodecanethiol (DT) solution under mild conditions. A series of superhydrophobic cotton fabrics, filter paper and melamine sponge were thus obtained water contact angles (WCA) 156.7 ​± ​2.1°, 151.5 ​± ​2.5°, 153.7 ​± ​2.7°, respectively. The application performance in self-cleaning, oil-water separation, and oil collection has been studied. In this universal strategy, amine-containing crosslinker PEI and APTES played dual roles as both regular aggregation to a uniform LT thin film and increase the absorption of LT. Particularly valuable features of this protocol including mild conditions, easily available and green benign material, simple execution, broad substrate scope, and easy reusability of products make it an efficient and promising universal strategy to construct superhydrophobic materials.

Architecting a Janus biomass carbon/sponge evaporator with salt-rejection and ease of floatation for sustainable solar-driven desalination

A Janus biomass carbon/sponge (JBCS) solar-driven desalination system is composed of carbonized original leaf particles and commercial melamine sponge seamlessly integrated with each other by a simple “soak-dip” method.

A sustainable strategy for the remediation of oil/water separation using polybenzoxazine/stearic acid functionalized porous carbon

Fabrication of superhydrophobic and superoleophilic polybenzoxazine-stearic acid based melamine sponge for industrial oil/water pollution treatments.

Versatile and cost-efficient cleanup of viscous crude oil by an elastic carbon sorbent from direct pyrolysis of a melamine foam

Carbon sponge with photothermal and Joule thermal properties was prepared by pyrolysis of melamine sponge. The significantly decreased viscosity of crude oil from heating enables a rapid and continuous crude oil cleanup under all weather conditions.

Preparation of caffeic acid-polyethyleneimine modified sponge for emulsion separation and dye adsorption

Water pollution has become a serious problem in aquatic ecology due to the oil spills and the consistent release of industrial pollutants, such as dyes. Herein, we report a simple method to fabricate superwetting caffeic acid (CA)-polyethyleneimine (PEI)-modified melamine sponges (CA-PEI-MS) for oil-in-water emulsion separation and dye adsorption. The as-fabricated CA-PEI-MS exhibited superhydrophilicity with an approximately zero water contact angel (WCA) and underwater superoleophobicity with an underwater oil contact angel (UWOCA) greater than 150°. The compressed CA-PEI-MS showed an excellent oil-in-water emulsion separation performance with a separation efficiency greater than 97% and a water flux of up to 25,480 L h−1 m−2 bar−1. The recyclability test was used to study the stability of the compressed CA-PEI-MS, after washing with acetone; the flux did not show any significant change during the 12-cycle separation test. The separation efficiency in every cycle was greater than 97%. Due to the availability of rich positive charged amino groups, the as fabricated CA-PEI-MS exhibited adsorption ability towards negatively charged dyes such as, rose bengal (RB) and direct red (DR) with 96% adsorption efficiency. Therefore, the as designed low-cost and eco-friendly preparation of CA-PEI-MS has a great potential for practical application as it shows high separation performances and excellent efficiency.

Polyurethane macro-encapsulation for CH3COONa·3H2O-Na2S2O3·5H2O/Melamine sponge to fabricate form-stable composite phase change material

Using nano-sized porous supporting materials as carriers to shape-stabilize phase change materials (PCMs) is leading currently. However, the high carrier proportion and the existence of “nonfreezing liquid layer” in the composite significantly reduce the phase change enthalpy of composite. In this work, macroporous Melamine sponge (MS) as lightweight semi-adsorbed supporting material and the eutectic hydrated salt of Na2S2O3·5H2O-CH3COONa·3H2O as PCM were introduced, and the enthalpy reduction of the PCM@MS composite was much smaller (within 5%). Subsequently, the solid polyurethane (PU) thin-layer was adapted to macro-encapsulate PCM@MS, by which PCM operated stably in a closed system, solving the leakage problem and eliminating salt corrosion. With the addition of 2% SrCl2·6H2O as nucleating agent, the eutectic hydrated salt PCM with the mass ratio of 72%Na2S2O3·5H2O-28%CH3COONa·3H2O processed a suitable melting point (41.45 °C), high enthalpy (186.6 J/g) and low supercooling (0.462 °C). The morphology of MS and the distribution of PCM in MS were investigated in detail. Leakage and thermal stability tests for PCM@MS@PU indicated that 2.5 mm PU thin-layer owned a prominent cladding effect on PCM@MS. Heat conductivity determination manifested that PCM@MS@PU presented a brilliant thermal insulation property. Moreover, its thermal performance difference was small after 150 thermal cycles. All these enable the application of PCM@MS@PU in radiant floor heating system and provide a new routine for shape-stabilizing PCMs with polymer-based macroporous supporting material and thin-coating material.

Adsorptive and responsive hybrid sponge of melamine foam and metal organic frameworks for rapid collection/removal and detection of mycotoxins

Mycotoxins have been regarded as one of the most severe threatens to food safety and environment, however, conventional detection methods are limited by low collection efficiency and tedious detection procedures. In this work, adsorptive and responsive hybrid sponge was prepared by integrating porous fluorescent Zr-LMOF (luminescent metal-organic framework) and robust melamine sponge for simultaneous collection/removal and detection of mycotoxins. The hybrid sponge achieved high load capacity of 15.8 mg g−1 within 10 min and worked well in a wide range of pH and temperatures. The fluorescence of the hybrid sponge was efficiently quenched by AFB1 in the aqueous water in 10 min due to the hierarchical pore structure enabled absorbent-target interaction. This simple, robust and low-cost dual functional hybrid sponge enabled the detection with relatively low LOD of 1.6 ppb and wide linear range of 31.2 ppb-15.6 ppm. Additionally, AFB1 in water was quickly absorbed by the Zr-LMOF crystals on the melamine microfibers with the removal efficiency reached as high as 90%. The removal efficiency towards other mycotoxins including aflatoxin B2, aflatoxin G1, aflatoxin G2, aflatoxin M1 and ochratoxin A also reached 80%. Overall, this low-cost, robust and elastic hybrid sponge has great potential in the construction of novel sensors for practical applications to ensure environmental and agricultural safety.

Shish-Kebab-Structured UHMWPE Coating for Efficient and Cost-Effective Oil-Water Separation.

High-performance low-cost superhydrophobic sponges are desired for selective recycling of leaking oils from open water. Herein, an ingenious method is proposed to fabricate an ultrathin superhydrophobic coating layer on a commercial sponge. The coating layer is composed of a shish-kebab-structured porous ultrahigh molecular weight polyethylene (UHMWPE) film that is fabricated from a UHMWPE/xylene solution by shear flow-induced crystallization. A strong relationship between the shish-kebab crystallite morphology and the superwetting performance is confirmed. The UHMWPE coating layer fabricated at a 900 rpm rotation rate possesses a lamellae size of 95.1 nm and a lamellae distance of 27.4 nm, which lead to a high water contact angle of 157° and a low contact angle hysteresis of 4.5°. The UHMWPE layer prepared in 4 min of treatment is thick enough to prevent the intrusion of water even under vacuum and remain superoleophilic. The developed UHMWPE-coated sponge (UCS) exhibited a high absorption capability of 70-191 g/g toward various oils and solvents, which is comparable with the neat melamine sponge. Its excellent compressibility and durability enabled fast recovery of absorbed oil with a high recovery rate (over 85%) by mechanical squeezing. The UCS could be assembled into small devices to selectively collect oil from open water and a water/oil mixture using a pump, which manifests its promising practical applicability. Apart from these extraordinary properties, the approach developed has the lowest material cost and the shortest processing time hitherto.

3D multiscale sponges with plant-inspired controllable superhydrophobic coating for oil spill cleanup

A facile and universal layer-by-layer self-assembly method was used to construct superhydrophobic sponge. This superhydrophobic sponge can be fabricated by surface functionalization of melamine sponge with gallic acid (GA) and iron (Fe) ions chelate for the enhancement of its micro/nano roughness first, followed by incorporation of hexadecyl thiol (HT) to achieve surface superhydrophobic modification. The GA-Fe-HT melamine sponge exhibits high adsorption capacity as much as 65–105 times its own weight for various oils/organic solvents. This coating endows the substrate with stable superhydrophobicity and reusability. After 100 times extrusion adsorption test, the modified porous melamine sponge still shows superhydrophobicity and good oils/organic solvents adsorption capacity. It is exciting that this superhydrophobic coating exhibits excellent hydrophobic properties after long-term treatment with strong alkali, strong acid and salt solution. Additionally, this eco-friendly, highly-efficient and low-cost design strategy can be applied for various substrates to prepare hydrophobic interface. The results obtained in this work will have a good promising prospect for many environmental applications.

PDA-PEI copolymerized highly hydrophobic sponge for oil-in-water emulsion separation via oil adsorption and water filtration

Oil adsorption from oily wastewater using three-dimensional porous materials is a popular mode of separation, but the adsorption of oil droplets from oil-in-water (O/W) emulsions is difficult. In this study, hydrophobic melamine sponges, prepared by coating with dopamine (DA) and polyethyleneimine (PEI) via controlled copolymerization, were utilized to separate O/W emulsions on a self-designed “oil adsorption-water filtration” device. Unexpectedly, the sponge obtained via DA/PEI modification was highly hydrophobic. Molecular dynamics simulations revealed that this was due to Schiff base production upon copolymerization of polydopamine (PDA) and PEI on the melamine sponge. The sponge showed excellent adsorption capacities, 67.2–178.6 times its own weight, for various oils. More importantly, a surfactant-free O/W emulsion was separated with 93.5% separation efficiency and 24.9 g/g sponge oil adsorption. The sponge also exhibited perfect separation efficiency for an anionic-surfactant-stabilized O/W emulsion. During filtration, negatively charged oil droplets were captured on the amino-rich sponge by electrostatic attraction. Furthermore, the hydrophobic effect was found to be the driving force in adsorbing and collecting oil on the sponge skeleton while repelling the continuous water phase. Since the as-prepared sponge can simultaneously adsorb oil droplets and filter the water phase in O/W emulsions, it has major potential for application in oily wastewater treatment.

Polydopamine mediated modification of manganese oxide on melamine sponge for photothermocatalysis of gaseous formaldehyde

It is an urgent need to develop environmentally friendly strategies with low energy consumption for gaseous formaldehyde (HCHO) purification. Herein, a sponge based MS/PDA/MnOx catalyst with plentiful 3D porosities was constructed. The dual-functional PDA layer not only promoted the MnOx loading (25 wt% MnOx in the composite), but also acted as a photothermal converter to absorb photo-irradiation to heat MnOx catalyst (~80 °C after 10 min irradiation). Moreover, the 3D network structure favored the mass transfer and effectively reduced the catalyst agglomeration to expose more active sites. As a result, the obtained MS/PDA/MnOx photothermocatalyst showed highly efficient performance for removal of HCHO within concentration of 40–320 ppm at room temperature under xenon light irradiation. This process followed a pseudo-second-order model, and the reaction rate of the MS/PDA/MnOx was 4.82 times of the MS/MnOx. Finally, a possible photothermocatalysis mechanism was proposed based on the intermediate examination via the in-situ DRIFTS investigation.

Ultralow-density carbon foam composites with bean-like Co-embedded carbon nanotube whiskers towards high-performance microwave absorption

We describe the design and fabrication of an ultralight carbon foam composite with special bean-like Co-embedded carbon nanotube whiskers used for high-performance microwave absorption materials. A facile approach was developed to create this carbon foam with the self-growth of carbon nanotubes on low-cost cobalt-decorated commercial melamine sponges (MF) via a simple thermal annealing process. It was found that a large number of bean-like carbon nanotubes whiskers (1D) embedded with Co nanoparticles (0D) grew on the surface of carbon skeleton (3D) under the action of surface autocatalysis. This unique hierarchical micro/nanostructure not only reduced the density of the materials but also effectively improved their thermal oxidation stability and microwave absorption ability. The resultant foam showed an excellent microwave absorption performance with the combined advantages of ultralow density (9.4 mg/cm3), strong absorption (minimum reflection loss value of −46.2 dB), wide absorption width (4.8 GHz), and high thermal oxidation stability (>350 °C). The RL values of the foam could be all below −10 dB at the frequency from 4 to 18 GHz covering 87% of the whole test frequency range. These remarkable results also provide a potentially scalable, simple, and cost-effective strategy for designing metal-embedded carbon composite nanostructures for catalysis, electrochemistry, and other applications.